Primary Sources - "materials on a topic upon which subsequent interpretations or studies are based"
Research Results generated by experiments
Secondary Sources - analyze or restate primary sources. They often attempt to describe or explain primary sources. Some secondary sources not only analyze primary sources, but use them to argue a contention or to persuade the reader to hold a certain opinion.
Books and articles that interpret, analyze, or review research.
Newspaper and magazine articles
In the sciences, an experiment or study is primary source. An article that reviews and summarizes several studies or experiments conducted by other people is a secondary source.